1. Field of the Invention
The invention relates to an optical disc drive; in particular, an optical disc drive with a mechanism to allow a tilt angle between its optical pickup and turntable to be optimized.
2. Description of the Related Art
For optical recording and reproduction, an optical disc drive can read recorded information from optical discs such as LD (laser disc), CD (compact disc), DVD (digital versatile disc, or digital video disc), or the like using an optical recording medium. There also is a compatible disc drive which can read information from any one of those optical discs.
Among these optical discs, a numerical aperture NA of an objective lens, a thickness of substrate, an optimum reading laser beam wavelength, and the like are dictated by different specifications. To realize an optical pickup of a CD/DVD compatible drive, therefore, it is necessary to compensate at least two differences of the numerical aperture NA and the substrate thickness.
As stated above, an optical pickup for accessing both CD disc and DVD disc must include two light sources generating a different wavelength of light beams and two objective lenses with a different number of apertures. In the case where an optical pickup is provided with two light sources and two objective lenses, there are problems in that as the dimension of the optical pickup is enlarged, its structure becomes more complicated and manufacturing costs thereof increase. In order to solve the problems, there has been developed an optical pickup capable of making use of a single light source and appropriately controlling thenumerical apertures of the objective lens depending on the corresponding disc.
In addition, when the disc is placed on a tray and inserted into the disc drive, the disc within the tray is clamped on a turntable. Then, the optical pickup is guided by guide rails along a radial direction of the disc, and carries out a seek operation.
In this type of disc drive, a relative angle between the optical pickup and the disc must be adjusted so that a distance between the optical pickup and the disc loaded on the turntable becomes constant, in order to accurately read the information recorded on (that is, pit pattern formed on) the disc.
In other words, in an assembly line of the disc drive, after the turntable, the optical pickup and the like are assembled, a reflected light from a reference disc used for the positional adjustment is detected by the optical pickup in a state where the reference disc is clamped on the turntable. In this state, the mounting angle of the turntable is adjusted while a measuring unit (automatic collimator) measures an angular error of the reflected light from the reference disc detected by the optical pickup, so that the angle of the reflected light from the reference disc becomes a prescribed value.
A description will be given of a conventional tilt adjust mechanism applied to the disc drive.
FIG. 1 shows a conventional optical disc drive. The optical disc drive as shown in FIG. 1 comprises a spindle motor 10a, a first plate 11a, a screw 12a, a second plate 13a, and a spring 14a. The spindle motor 10a is disposed on the first plate 11a. The screw 12a is locked to the second plate 13a through the first plate 11a. The spring 14a is disposed between the first plate 11a and the second plate 13a. The screw 12a can adjust a tilt angle of the spindle motor 10a. 
However, by means of the screw 12a, the tilt angle of the motor 10a cannot be accurately adjusted.
FIG. 2 and FIG. 3 show another conventional optical disc drive. The optical disc drive as shown in FIG. 2 comprises a guide rail 20a, a spring leaf 21a, a first screw 22a, a support 23a, a plate 24a, and a second screw 25a. The guide rail 20a is assembled with the spring leaf 21a at both ends. The spring leaf 21a is fixed on the support 23a with the first screw 22a passing through. The second screw 25a is disposed on the plate 24a and used to adjust a tilt angle of the guide rail 20a so as to optimize a tilt angle of an optical pickup of the optical disc drive.
However, in the optical disc drive as shown in FIG. 2 and FIG. 3, since the number of components is increased, costs are also increased.
In order to address the disadvantages of the aforementioned optical disc drive, the invention provides an optical disc drive with a tilt adjust mechanism so that tilt angle between the optical pickup and turntable can be optimized.
Accordingly, the invention provides an optical disc drive. The optical disc drive comprises a base plate, a plurality of mounts, two guide rails, a plurality of pre-compressed springs, and a plurality of screws. Each of the mounts is disposed on the base plate. Each of the guide rails is disposed on the mount. Each of the pre-compressed springs is disposed in the mount. Each of the screws is disposed on the base plate through the mount and the pre-compressed spring so as to adjust the guide rail.
In a preferred embodiment, the optical disc drive further comprises a plurality of supports. Each of the supports is disposed on the base plate, and each of the mounts is disposed on the support.
It is understood that each of the mounts is of plastic.
In another preferred embodiment, each of the mounts includes a first hole into which the guide rail is inserted.
In another preferred embodiment, each of the mounts includes a receiving portion and a second hole communicating with the receiving portion so that each of the pre-compressed springs is disposed in the receiving portion and each of the screws passes through the second hole and the pre-compressed spring.
In another preferred embodiment, this invention provides a tilt adjust mechanism for an optical disc drive. The optical disc drive includes a base plate. The tilt adjust mechanism comprises a mount, a guide rail, a pre-compressed spring, and a screw. The mount is disposed on the base plate. The guide rail is disposed on the mount. The pre-compressed spring is disposed in the mount. The screw is disposed on the base plate through the mount and the pre-compressed spring so as to adjust the guide rail.